This invention relates to novel trivalent metal salts suitable for use in various forms of antiperspirant compositions, such as creams, lotions, sticks, pads, powders, aerosols and non-aerosol formulations. This invention further relates to the method of manufacture of such salts and antiperspirant compositions including the novel metal salts of this invention.
Reduction of perspiration flow is dependent upon astringent action in most commercial antiperspirants. The mechanism of this astringency is not well understood. The most popular explanation is that astringents, whose action is limited to the cell surface and the interstitial spaces, by reacting with proteins of the skin cause coagulation and swelling with blocking of the openings of the sweat glands, thus reducing the flow of perspiration. Another explanation is that astringents act directly on the sweat glands, causing inflammation and swelling, thus causing expansion of the stratum corneum around the sweat duct and the orifice, this expansion impeding the sweat flow to the surface. Recent studies have shown, however, that very little active ingredient reaches the dermal layer, which would tend to rule out the theory that the astringents act directly on the sweat glands, and thus limiting the astringency effect to a topical one.
Inorganic salts that have proven to be the most popular in controlling perspiration include the salts of aluminum, zinc, and zirconium. The metal ion of the salt has astringent properties and is responsible for the reaction with the skin tissue to cause coagulation of skin protein. Astringency also appears to be dependent on the anion selected. Among the most commonly employed anions are the chlorides, hydroxychlorides, sulfates and sulfamates.
The most widely used basic aluminum salts are the aluminum chlorohydrates, aluminum chlorohydroxylactates, formed by complexing aluminum chlorohydrate and sodium lactate, basic aluminum bromide, and the aluminum chlorohydrate-propylene glycol and polyethylene glycol complexes. The basic aluminum salts have been used either alone or in admixture with each other and/or complexed with other astringent materials such as aluminum chloride and zirconium hydroxychloride, in antiperspirant preparations.